3 Citations (Scopus)

Abstract

Oxides with pyrochlore structure are promising materials for SOFCs, oxygen and hydrogen separation membranes, and other devices. Ln zirconates attract interest due to their oxygen and protonic mobility. In this work, oxygen transport mechanism in Mg-doped Sm and Gd zirconates was studied. Sm1.9Mg0.1Zr2O6.95 and Gd1.9Mg0.1Zr2O6.95 oxides have been prepared via the mechanical activation and characterized by XRD, TGA, and SEM. Oxygen transport features were studied by the oxygen isotope exchange with C18O2. Isotope substitution of bulk oxygen was demonstrated to be described by the 2D diffusion model. Very fast diffusion within grain boundaries provides fast isotope label distribution over the oxide domains, then tracer distributes due to a slower diffusion within domains’ bulk. Three forms of oxygen were distinguished within grains’ bulk. Very fast diffusion along grain boundaries (Dgb ~ 10−7 cm2/s at 700 °C) can provide high rates of oxygen transport in oxygen separation membranes.

Original languageEnglish
Pages (from-to)4621-4633
Number of pages13
JournalIonics
Volume26
Issue number9
DOIs
Publication statusPublished - 1 Sep 2020

Keywords

  • 2D diffusion
  • Diffusion
  • Isotope exchange of oxygen
  • Modeling
  • O conductors
  • Pyrochlores
  • ELECTRICAL-CONDUCTIVITY
  • ANOMALOUS TRANSPORT
  • NEUTRON-DIFFRACTION
  • RELAXATION
  • PROTON
  • NONSTOICHIOMETRIC PEROVSKITES
  • OXIDE PYROCHLORES
  • GRAIN-BOUNDARY
  • DEFECT CHEMISTRY
  • ION CONDUCTIVITY

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